I literally stopped 8 months of lurking and created an account here just to post this, so here goes:
-MINOR SPOILERS-
So, there's no solid proof that Double was killed the last time the Skullheart was destroyed, leading to the belief that she's been around for some time, waiting patiently every 7 years for the Skullheart to re-emerge. During that time there's not much she could've done besides the occasional set-up and plotting, so i like to think that she got into TV shows. One of her favourite things to watch was actually NMO Wrestling, where she got to know the Gigan Slayer Beowulf. She became really invested into wrestling which may have inspired some of her moves, but the important thing to note is that 7 years later when the latest Skullheart reappears and a certain retired legend comes bursting through the Cathedral doors looking for a nun, she immediately recognizes him.
It makes sense on a retrospective scale. Double removes the Skullheart's influence from Grendel's arm almost immediately, an act of sympathy unlike Double's usual personality. Why would she help Beowulf instead of just watching him thrash around trying to wrestle the Skullgirl-influenced limb? She aids him in calming it down and asks him to renounce it and leave. When beowulf refuses and instead announces his comeback plans, Double gets a plan.
Then comes the second bit of the evidence: How does Double know so much about Beowulf's life? She knew Zane was his old agent, exactly how he talked and acted and as Zane she frequently alludes to Beowulf's wrestling past IN DETAIL.
She then manipulates Beowulf into fighting some of the cast for her, including Big Band and Painwheel. Now, if Double had the same thought process as 80% of the cast had, she'd realize Beowulf is just a regular guy and that pitting him against a Skullgirl hunting veteran would be a huge mistake, but she KNOWS that Beowulf is exceptionally skilled and has the stuff to keep Big Band occupied while she and Valentine storm Lab 8. Even after she fights him and traps him in Gehenna, she refuses to subdue and wrap him in tentacles like the rest of the people there. She just flat out tells him to sit down and get comfortable cause he's gonna be here a while.
Why? Because Double spent a good half of her waiting time watching Wrestling, and Beowulf is to her what Annie is to Peacock. Double is probably secretly fangirling on the inside whenever she gets to talk to him. She's a bigger fan than Cerebella.
EDIT: Formating
